Smith



A. N. GOLDSMITH AND J. WEINBERGER.

RADIO RECEIVING SYSTENL APPLICATION ILED SEPT. 13, 1918.

1,396,571 a A Patented Nov. 8, '1921.

ALFRED N. eonnsmrsr AND JULIUs wnmnnnenn, or NEW YORK, v1\T.Yl, AssIcNons 'ro GENEBALELECTRIC coMrANY, A conronarron or Naw Yorin.

Ramo nEoErvING sYs'rEM;

' Specication of Letters Patent. Patented NOV, 8, 1921,

Application led September 13, 1918. Y Serial NW2-53,938.

Be itrknown that we, ALFRED N. GroLns'MrrH and JULIUS WEINBERGER, citizens of the United States, residing at New York,

county of New York, State of New York,`

' and F 1g. 5 shows an arrangement which have invented certain` new and `useful Im- Y provements in Radio Receivin Systems, of

which the following is a speci cation.

Our present invention relates toradio signaling systems and particularly to a receivingsystem which is adapted for use in a duplex system.

The object of our invention is to provide a receiving system which is adapted vto be used' in close proximity to a transmitting system and whichvis capable of receiving signals from adistant station at the same time thatsignals are being sent from the transmitting station; 2O

In vduplex radio telegraphy or telephony,

the object sought is the simultaneous reception and'transmission of messages. In most cases. 1tY hasheretofore been customaryv to V,accomplish the object by havingtwo .sepa- A 2.5

rate'stations;"a transmitting station and a xreceiving station separated by many miles andusually'connected by wire lines. This `procedure has been necessary inlorder lto prevent the transmitted signals from interfering with thereCeptiOn of the desired signals.

This interference is due to both the electric and magnetic fields of the local trans. If a receiving system of mitting antenna the interference is largely electrostatic in nature. That is, the capacitive'lexposure of the receiving systemV to the transmitting antenna causes charges to 'be induced therein which give rise to the interference in question. In carrying out our invention the effect of this capacitive induction `is eliminated by the use of an 'electro-V be characteristic of our invention are set balanced Vclosed loop or coil re- .forth with particularity in the appended claims. The invention itself, however',v both as to its organization and method of operation will best be understood by reference to the following description taken in connection with the accompanying drawing in whichFigurell shows diagrammatically one Wayin whichv our invention may be carried into effect; Figs.y 2 and 3 show different types of receiving coils which may .be used; Fig. 4 shows diagrammatically a circuit arrangement which may-be employed in connecting the duplex system to a wireline;

may be usedv for'overcoming the effectof electromagnetic induction as well as electro-L static.

' In the arrangement shown in Fig. 1,;the

`transmitting antenna is indicated by l, and

2is the coil employed for reception. This tuning condenser 6 may be used fortuning the receiving circuit to the. frequency of the ,signals to be .received The plate circuit of the amplifier 5f comprises the cathode 3 Aof the amplifier, a local source of current 7,

a wave responsive device 8 and the anode 9 of theampliiier. The grid 4 isconnected to one end of the coil 2 and the cathode 3 is connectedto the junction point of the two halves of coil 2 tov ground, the magnetic` fields `of the two halves are in opposition and the two halves of coil 2 act as indue'- tances in parallel. The inductance of the where coil\for such currents then is 2 and M is the mutual inductance between the two halves. If M is made equal or very nearly equal to L then the coil 'becomes'a non-inductive path to ground for capacitively induced currents; consequently no potential difference can build up across its terminals and no interference will result in the receiving set from the local antenna.

While the capacitive induction fromthe local antenna will be balanced in this manner, a totally different behavior occurs toward the signals to be received. In the Vcase of the local antenna we deal with a stationary electric field, inasmuch as radiation commences only outside of the quarter wave length zone; in the case of the distantantenna, a traveling electromagnetic wave .coil is connected'to the Acathode 3 and grid 4 of an electron discharge amplifier 5. A

itis

Y coilfthe're" will ,hepronced en Yelectromotive y Y rcefvvhich Yvariesifin z plitudeand phase v' YY fromnthet 'induced in-,every otheiY element.,Y Y Some oijthese electromotivefforces YWillfper-V n Y 'entelectroniotive force 'will cause e currentV ti'eillyraneutrallize each other but -tthegr'esultg tooiv `in the, receivingfcircuitf, In practice Y Y it' is Yfourni? that* the neutralization will beV Y minimized kbymakingfthe,coil ot large .dijf,y Y V2715A mension's-in the directionoitherzweve and Y'will not. f In Figi Y2 employed Leach? of the type known as pene` bylY Whichle thorough capacitive i transposi- Y so'gconnected vrthat :theirfmegnetic fieldsy edd V ih nt successive coilseretraneposed to;either; side )of rthel neutral l.ors grounded point in orderlto Y effectively equlize or", belence'f the Y v'capeciti've 2 exposure the combination;

i Y VAnother' methodYY of `cerryinig; outoun in; Y Vventionf1s1to`1nekefy thegreceivingcoil ofar ,paire off; wires 12` twisted together. asin'di' Y. i nIIiY'Elgxyl we have,indicatoridiegrammati-VV Y cellythe .manner in .which the receivingrand- Y transmitting apparatus mayheconneetedjto VeerYgWrlI'ellne Yto connect ay subscrihers` tele;` Y

i phonegfor example', to :thedupiex system.

tors 13 ere also connected to :the output ter-y Initialsy 17 'of the receiving` epparetus Y18VV Vwhich iis controlled bythe receivingcoil Vi2; and the amplier, Y A

l letter is strong enoughto, canlsetronlole; the VVVreceiving lcoil may plncedfingsuche' poshV .i

i @thatL the. vlerger .the dimensions if ofV thefrcoily Vboth finiy a, horizontei,andY vertic'al Ydirectiornthe'stronger thcfsignls will he.y Y

- 'llt-isepperentffromtheaboveexplenation 20 thlet fthe f induction Afromk the 'local transc' l mittirig antenna, Y that-vis Yinduction due toJa *Y fl fste'tioneryr electric ielclA ,wiil' Ybe balanced. out I o Y. Y but@ the i inductionfromV 'the distnt antenna 7 Y fedueftofthe Y. traveling electromagnetic waves f Y Y Y s Y, y .Y -thatmany modiic'ationsiini the #mennen in f A We'h'av'e shown yan eiiicient wey whichour invention is applieclmeyb made 3 of obtaining, a g perfect equalization ofthe h i exposure zof Vtheztwohalves ,of the coil; Inr LVthis Y case i aYYplurality Vof lAmit coils:V l1 are'4 l Ycakesvor-Spiralsf These are multifleyerf F Y VYsolenoids .with one or only; e 4fevveurns paryYelleijfto Ytheexis ofthe solelioidjy The coils ,Y Y Y areconnectefi inseries inthe manner showin.V i" Y i tioni's(obtained.V` Thotv is` the unit coilsrare in pended claims. 'Y

Y receiving Y, loop i' antennefliiiviiig,V 'tWOf helv Y l i Y receiving lloop' antennahavingtvvofhalvesfl yoithe-two halvesoffY Y Yhalves,e ground connectionQtogrthefjunctionx c cated YinYFigl 3,"and ,use only .one ofl these ',Y Y i Wires forreception. It isY apparent thatthe Y,

'Y transpositionof the twojhalves'othe-winx#- i ing'will!he'broughtl about fi'nfthis' We'yf'evenVV 'more ifcctivelyrthan by the forni shown; in f f Ypointer. thetwohelves Yr heling system j or' a trensrnittlngYkanteniL-a.,'v a receiving zooil located im fcloseA proximity;Y Y

, v y Y 1 largemutuel indnctencegbetweenvthe helves,f

The incoming line 1s represented bythecon-E y Y' fj ductrel which are'connectedl-rto thefiuput` Y terminale 14 of thetrans'mitting apparatusk 157,?y thegoutpnt terminals 16 of ivvhicherevk s VconnectedY to the antenna 1'." The.conclue-fV gthe two halves end receivingngppereltns'no Ybetween the portions'yy saidfY portions 1hevingleoY Y I' .'Whiie the eii'ect ofV electrostatic induction' I will.l in most ceses 4be -muchrmore l'rrmlble-Y some than vthat duegto Athe @magnet-ic *Ytielrlx fromy the feedWiresfofftheientennegfif theYYVYV 'g tionreletivetothe feedy nrethat'tliellrlfigf1VV i" neticr inouction. duegto; he gloceirentenne ne Yf a. minimum Whiie 'the Heft/ofthe clistant if? Y stationf'is ef maximum.- Thisi restritngay bei; 75`

e attained Ybyy inenting; the receiving lcoil2 inVv such a YWav that 'its axiisf pointsftoward the feed Wire of the local Vstsrition-enti inge. dir'eoffQ tion at right angles to@Y the 5 direction? ofthe: n distant istetion; A 'Y This4i in'elnner fY of locating Y Ythe;receiving Icoil-fis indicetedvin lQF .firr 'Wllichil indicetesthefeed' Y ntenna, 2V the recelvlnglco ie'foftheflocel Y 1d mille'. dis- 'tant transmitting entenna., r

e Vfew examples Yof the manneriinwvhich; ourw'vv invention: ,may be fear-ricciY into'- effect; .we ido notirwish tojbe limited tothe pnrticnler el?- ran'gem'ents l'shown (as .it Yw'ill 'lie-gj, epparent Y Withouty depk listingv from kthe scope of Qt ,i YWliet reclaim afg; new-end ,Ydesiregto' byve Letters :PatentrofatheglniredrStaten; Y

Y' VY1.Y A radio receiving sg'steriri[comprisiIigy a with. large mutuel inductance-f betweenA the 'halves and a groundYconnectiontofthejnncr tion pointf'lo'f the Yt'vvo' halvefsso :es-toproviie f a. substantially Lnon-r,inductiisfeperth'to ground for currents induced intheloop by capaci= tiveYinduction.eYV Y i VV 2.7, A radioYreoeiving Ysystemicomprisingge with lergemutlil yinductence between iftlief point or the twofh'alves end'kreceivinggappe-j Y* Y Yratus'connectedftoone-of thehalvesonly.;Y Y

.The combinationiin e -duplex1redio sig# nailing; system of a ltren'smitting antenne and a l receiving f coil 1located' in' Yvclose proximityz A thereto, Vsein?V coil comprisingftvvophelves" withl large mutuelV inclue'tancebetween Qthe halves.- and e ground icormectiongY to2: tlief junctionj e i. y The combination Yin daplexgrdie sig;

thereto, seid coil comprisinglgtwol helve'asirvvith'Y Y' e groixnd connectiontorthejnnction:point of nected to one of the helvesfon1y.i Y .Y 57.? The combination in'agd lex'Yrelioys'igig naiing systemroi a Y'trensrnittin'g'` antenna, and a receiving; lcoil loceted iniy 'close proiel iinity thereto, seid receiving kcoil comprising; fewo,portionsy with largey niujitnelincluetence'A substantially equal capacitive exposure to the transmitting antenna and a ground connection to the junction point of the two' portions. 4 v

6. The combination in a duplex -radio signaling system of a transmitting antenna, a receiving coil located in close proximity thereto and having its axis extending toward the feed wire of said antenna and in a direction substantially at right angles to that from which signals are to be received, said coil comprising two portions having-,sub-

stantially equal capacitive exposure-to the transmitting antenna and a ground connection to the junction point of the two p0rtions.

7 A receiving antenna consisting of a coil having a plurality off turns divided into two substantially equal groups connected in series with each other and forming part of an open circuit, and a ground connection to the junction point of the two'groups.

8. A receiving antenna consisting of a coil having a plurality of turns divided into -two substantially equal groups connected in coil having a'plurality of turns divided into two substantially equal groups, the mutual inductance between said groups being substantially equal to the self induction of each group, and a ground connection to the junction point of the two groups.

In witness whereof, we have hereunto set our hands this 10th day of September, 1918.

ALFRED N. GOLDSMITH; JULIUS WEINBERGER. 

